1. Field of the Invention
The present invention relates to a Francis type hydraulic machine of the type traversed by a main flow of water, comprising a wheel of a turbine in the vicinity of which is formed at least one eddy zone or a reduced-pressure zone or a cavitation zone, the wheel comprising blades arranged between a ceiling and a belt, the machine comprising means of injecting a flow tapped from said main flow, not modified relative to the main flow, into said eddy or reduced-pressure or cavitation zone so as to locally modify the main flow or increase the pressure in this zone.
2. Brief Description of the Related Art
Such a machine is used, for example, in a plant for producing hydroelectricity. The machine is installed in the path of the current or is supplied with water from a reservoir into which one or more water courses are discharged.
In these hydraulic machines, there are zones in which the main flow traversing the machine is disturbed and forms eddies or exhibits a reduced pressure or cavitation zones, because of the configuration of the machine. Such zones disrupt the general performance of the hydraulic machine because they reduce the efficiency of action of the main flow in the hydraulic machine or cause problems of operation of the hydraulic machine.
The document U.S. Pat. No. 1,942,995 describes a hydraulic machine of the abovementioned type, making it possible to inject a flow tapped from the main flow into the cavitation zone being formed along the blades of the wheel of the turbine.
However, such a machine does not make it possible to effectively increase the pressure in the spaces extending between the blades where reduced-pressure zones are formed or eliminate the eddy zones that are also formed between the blades.